Homoharringtonine deregulates MYC transcriptional expression by directly binding NF-κB repressing factor
Homoharringtonine deregulates MYC transcriptional expression by directly binding NF-κB repressing factor
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高三尖杉酯碱通过直接结合 NF-kappa B 抑制因子来解除 MYC 转录表达的调节
DOI：
10.1073/pnas.1818539116
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发表时间：
2019-02-05
影响因子：
11.1
通讯作者：
Chen, Sai-Juan
中科院分区：
文献类型：
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作者：
Chen, Xin-Jie;Zhang, Wei-Na;Chen, Sai-Juan
高三尖杉酯碱（HHT）是一种已知的蛋白质合成抑制剂，具有抗髓系白血病的作用，并可增强蒽环类/阿糖胞苷诱导方案对急性髓系白血病（AML）的治疗效果，尤其是t（8; 21）亚型。在此，我们提供的证据表明，HHT抑制t（8; 21）小鼠白血病模型中白血病诱导细胞（Lin（-）/Sca-1（-）/c-kit（+）; LIC）的活性，并对人t（8; 21）白血病细胞（Kasumi-1）中MYC通路基因发挥下调作用。我们发现NF-κ B阻遏因子（NKRF）通过其核定位信号的第二个双链RNA结合基序（DSRM 2）结构域与HHT直接结合。一系列缺失和诱变实验将HHT直接结合位点定位到DSRM 2结构域中的K479和C480氨基酸。HHT处理通过占据DSRM 2结构域将NKRF从细胞核（包括核仁）转移到细胞质，加强p65-NKRF相互作用，并干扰p65-p50复合物的形成，从而减弱p65对MYC基因的反式激活活性。此外，HHT显著降低KIT的表达，KIT是t（8; 21）AML中频繁突变和/或高表达的基因，与MYC下调一致。因此，我们的工作确定了HHT的作用机制，该机制不同于该化合物的已知作用模式，但与该化合物的已知作用模式一致。这些结果证明HHT在AML中的进一步临床试验是合理的。
Homoharringtonine (HHT), a known protein synthesis inhibitor, has an anti-myeloid leukemia effect and potentiates the therapeutic efficacy of anthracycline/cytarabine induction regimens for acute myelogenous leukemia (AML) with favorable and intermediate prognoses, especially in the t(8; 21) subtype. Here we provide evidence showing that HHT inhibits the activity of leukemiainitiating cells (Lin(-)/Sca-1(-)/c-kit(+); LICs) in a t(8; 21) murine leukemia model and exerts a down-regulating effect on MYC pathway genes in human t(8; 21) leukemia cells (Kasumi-1). We discovered that NF-kappa B repressing factor (NKRF) is bound directly by HHT via the second double-strand RNA-binding motif (DSRM2) domain, which is the nuclear localization signal of NKRF. A series of deletion and mutagenesis experiments mapped HHT direct binding sites to K479 and C480 amino acids in the DSRM2 domain. HHT treatment shifts NKRF from the nucleus (including nucleoli) to the cytoplasm by occupying the DSRM2 domain, strengthens the p65-NKRF interaction, and interferes with p65-p50 complex formation, thereby attenuating the transactivation activity of p65 on the MYC gene. Moreover, HHT significantly decreases the expression of KIT, a frequently mutated and/or highly expressed gene in t(8; 21) AML, in concert with MYC down-regulation. Our work thus identifies a mechanism of action of HHT that is different from, but acts in concert with, the known mode of action of this compound. These results justify further clinical testing of HHT in AML.